Vertically reciprocating door and actuating mechanism therefor

ABSTRACT

Apparatus for selectively controlling access through a protected opening in the wall of a cash dispenser housing, including a vertically disposed door reciprocable between an upper position in which the opening is uncovered by the door to permit access through the opening and a lower position covering the opening to prevent access therethrough; means vertically spaced proximate the opening and a detent mounted to the door for horizontal movement between an extended position engaging the abutment means and a retracted position disengaged from the abutment means; biasing means normally urging the detent to its extended position into engagement with the abutment means to prevent upward motion of the door; a motor and a cable engaging the motor and the door for elevating and lowering the door when the motor winds and unwinds the cable, respectively; and means connecting the cable and the detent for retracting the detent when the cable is tensioned by the weight of the door in the course of elevating or lowering the door.

United States Patent 1 Moorman et a1.

[ VERTICALLY RECIPROCATING DOOR AND ACTUATING MECHANISM THEREFOR [75] Inventors: Charles J. Moorman, Cincinnati;

. Myron D. Goldman, Kettering, both of Ohio [73] Assignee: TheMosler Safe Company,

Hamilton, Ohio {22] Filed: Sept. 17, 1972 [21] Appl. No.: 290,999

FOREIGN PATENTS OR APPLICATIONS Austria 49/197 July 24,1973

Primary Examiner-Dennis L. Taylor A ttorney-James S. I-light, Donald F. Frei et al.

[57] ABSTRACT Apparatus for selectively controlling access through a protected opening in the wall of a cash dispenser housing, including a vertically disposed door reciprocable between an upper position in which the opening is uncovered by the door to permit access through the opening and a lower position covering the opening to prevent access therethrough; means vertically spaced proximate the opening and a detent mounted to the door for horizontal movement between an extended position engaging the abutment means and a retracted position disengaged from the abutment means; biasing means normally urging the detent to its extended position into engagement with the abutment means to prevent upward motion of the door; a motor and a cable engaging the motor and the door for elevating and lowering the door when the motor winds and unwinds the cable, respectively; and means connecting the cable and the detent for retracting the detent when the cable is tensioned by the weight of the door in the course of elevating or lowering the door.

5 Claims, 7 Drawing Figures VERTICALLY RECIPROCATING DOOR AND ACTUATING MECHANISM THEREFOR This invention relates to a door and associated actuating mechanism, and more particularly to a door and actuating mechanism which prevents unauthorized opening of the door, yet will not injure a person in the path of the door under conditions wherein the door is closing under control of the actuator and/or due to actuator failure.

In the automation of banking transactions, particularly dispensing cash to a customer pursuant to a withdrawal from a savings or checking account, automatic equipment has been devised which, without human intervention of a teller or other bank employee, automatically dispenses cash to a bank customer in response, for example, to insertion of an identification card into the apparatus and the actuation by the customer of appropriate control buttons indicating, for example, the amount of money desired. Since such automatic apparatus does contain stored money, it is a potential target for thieves and vandals. While the theft and vandalism problem is not appreciable where such equipment is located in a protected area, such as the lobby of a bank, the problem is serious when the equipment is located in an unprotected area, such as on the sidewalk, where the apparatus is available on a 24-hour-per-day/7-dayper-week basis and normally unattended by bank employees or other security personnel.

In an effort to minimize the vandalism and theft problem, it has been found desirable to provide automatic cash dispensers with a door covering the dispenser control pane] and money issuing slot. The door, which is normally closed, is opened when a bank customer inserts an identificalion card in a suitable slot on the front of the machine, and remains open until completion of the cash dispensing transaction whereupon the door is closed. If security is to be maintained, closure of the door upon completion of the banking transaction must be automatic, that is, under machine control. This is in contrast to relying upon the customer to close the door upon completion of the transaction.

In the design of a door and actuating mechanism for a cash dispenser suitable for providing security against theft and vandalism, a number of criteria must be satisfiediFor example, it is essential that the door and actuating mechanism operate such that it will not injure a customers hand should the customer get his hand in the path of the door while it is automatically closing under machine control. Likewise, it is essential that the door and actuating mechanism operate such that it will atuomatically close should the actuating mechanism fail during a banking transaction when the door is normally maintained in its open position by the actuator. While it is desirable that the door close by itself in the event of failure of the actuator mechanism, it is also es sential that in the course of doing so it does not injure the hand of a customer which may be located in the opening in the path of the door. Finally, and quite importantly, while the door and actuating mechanism must be designed in the manner to accomplish the foregoing results, it must not be capable of being opened by an unauthorized person.

Accordingly, it'has been an object of this invention to provide a door and actuating mechanism therefor which resists unauthorized opening, yet automatically closes at the end of a banking transaction or should there be a failure of the actuating mechanism during a transaction, and does so without injuring the hand of an authorized user located in the path of the door as it is closing, either automatically at the end of a transaction or in the course of a transaction pursuant to a failure of the actuating mechanism. The foregoing objective has been accomplished in accordance with certain principles of this invention by combining a vertically shiftable door movable between an upper, open position and a lower, closed position; a detent mounted to the door for horizontal movement between an extended and retracted position; multiple abutments vertically spaced for cooperation with the detent, the detent and abutments being configured to prevent upward movement, while permitting downward movement of the door when the detent is in its extended position and in engagement with the abutment; a motordriven cable which engages the door for raising and lowering it when the motor winds and unwinds the cable; means connecting the cable and the detent for retracting the detent when the cable is tensioned while elevating and lowering the door; and bias means for urging the detent to its extended position only when the cable is untensioned to prevent elevating the door' when the motor unwinds the cable to lower the door, the door is in its closed position, or the cable becomes broken.

By virtue of the foregoing arrangement, when the door is in its closed position and the cable untensioned, the detents are biased into engagement with the abutment, preventing unauthorized opening. However,

when the door is in the process of being opened or closed by the cable, the tension in the cable due to the mass of the door suspended therefrom retracts the detent, permitting opening and closing of the door. Should a customers hand be in the path of the door when the door is closing at the end of a transaction, the door, because it is not being positively driven closed, will not crush the customers hand. Rather, it will stop at the position it is in when it encounters the users hand, and remain there until the hand. is removed, whereupon the door will complete its closing operation. Similarly, should the door-actuating cable break during a transaction when the door is normally held open by the actuator, a customers hand in the path of the door will not be injured since the door will stop when its hits the users hand. When the users hand is removed, the door will finish closing. Of course, were the cable to break while the door is open and the users hand not in the path of the door, the door would close without stopping. In either case, when the cable breaks and becomes untensioned, the detent is free to extend under the action of the bias means and engage the abutments. Under such circumstances, the downward motion of the door is retarded or delayed, although not stopped, as the detent sequentially engages and disengages successively lower abutments.

These and other advantages and features of the invention will become more readily apparent from a detailed description thereof taken in conjunction with the drawings in which:

FIG. 1 is a perspective view of the front of an automatic cash dispensing machine incorporating the vertically reciprocating door and actuating mechanism of this invention;

FIG. 2 is a cross-sectional view taken along line 2-2 of FIG. 1 showing the apparatus of FIG. 1 with the door in the lowered, or closed, position;

FIG. 2A is an enlargement of a portion of FIG. 2 showing the door guide and detent;

FIG. 3 is a rear elevational view of the door and actuating mechanism of this invention showing the door in the lowered, or closed, position;

FIG. 3A is an enlargement of a portion of FIG. 3 showing the detent in the extended position;

FIG. 4 is a rear elevational view of the door and actuating mechanism of this invention showing the door in the raised, or open, position; and

FIG. 4A is an enlargement of a portion of FIG. 4 showing the detent in its retracted position.

To more clearly understand the structure, operation and advantages of this invention, the invention is described in conjunction with its use in an automatic cash dispenser. With reference to FIG. 1, the cash dispenser is seen to include a housing 10, only the front of which is shown, having a control panel 11 accessible through an opening 12 formed in the housing. The panel 11 is located within a recess or cavity 13 in the housing defined by top and bottom horizontal rectangular panels l4 and 15 and opposite vertical rectangular side panels 16 and 17. The control panel 11 includes appropriate slots 18 and 19 from which cash 18 and a receipt 19', respectively, are dispensed to the customer or user. The control panel 11 further includes appropriate visual indicators and actuating buttons 20 which facilitate accomplishing such functions as selecting the amount of money desired and the particular account, e.g., savings, checking, or the like, to be debited. Located above the control panel 11 and constituting the upper rear back wall of the recess 13 is a stationary protective panel 21. Panel 21 extends between cavity side walls 17 and 16. Located behind the stationary protective panel 21 is a control panel cover, or door, 22 which is vertically disposed and movable between an upper, or open, position (shown in dotted lines in FIG. 1) permitting access to the control panel 11 and a lowered, or closed, position (not shown in FIG. 1) in which access to the control panel is denied. Located to the left of the control panel 11, and not covered by the door 22 when the latter is in its lowered or closed position, is a slot 23 formed in a stationary protective panel 24. Slot 23 receives an identification card 23. The card 23' when inserted in slot 23 is operative to elevate the control panel door 22 from its lowered or closed position to its raised or open position to permit the card holder to gain access to the control panel when use of the case dispenser is desired.

With reference to FIGS. 2-4, the control panel cover or door 22 is seen to include a vertically disposed rectangular planar sheet or panel 25, the margin of which is provided with two spaced 90 bends to form a rearwardly extending lip 26 which in cross-section has an inverted L-shape. The opposite vertical sides of the door 22, including the lip 26, are positioned for vertical sliding motion in stationary guides 27 secured to housing 10 forward of the control panel 11 adjacent the opposite sides thereof. Each of the guides 27 are C- shaped in cross-section.

Located within each of the guides or tracks 27 are vertically disposed locating and guiding trackways 28 which locate and guide the lip 26 of the opposite vertical sides of the door 22 such that the door remains captive in the guides or tracks 27. Both the C-shaped tracks 27 and the located and guide trackways 28 extend from the bottom 15 to the top 14 of the cavity 13.

Located in the upper portion of each of the guides 27 and in front of the trackways 28, are abutmcnts means in the form of saw-toothed racks 29 having saw-toothshaped teeth 30, which slope inwardly and downwardly. Cooperating with each of the saw-toothed racks 29 are detents 31 and 32 which are mounted to the rear surface of the front door panel 25 for horizontal sliding movement between extended positions shown in FIG. 3 and retracted positions shown in FIG. 4. The outermost ends of detents 31 and 32 project through slots 33 formed in the lips 26 associated with the opposite vertical sides of the door panel 22. In the extended position shown in FIGS. 2, 2A, 3 and 3A the outer ends of detents 31, 32 are positioned such as to engage the saw-teeth 30 of the racks 29 when the door 22 is in all but the fully closed position. In the retracted position shown in FIGS. 4 and 4A, the outer end of the detents 31 and 32 are withdrawn sufficiently inwardly to prevent engagement with teeth 30 of racks 29 in all vertical door positions including fully closed, fully open, and positions intermediate thereof. Each of the detents 31 and 32 are mounted to the rear surface of the door panel 25 for horizontal reciprocating motion between the extended and retracted positions of FIGS. 3A and 4A by a pair of pins 34 secured to and extending rearwardly from the rear surface of the door panel 25. Pins 34 are slidably positioned in horizontal slots 35 formed in the detents 31 and 32. v

The detents 31 and 32 are normally biased to their extended positions shown in FIGS. 3 and 3A by tension springs 36 and 37 operating through pivotal plates 38 and 39 and connecting links 40 and 41 in a manner to be described. Plate 38 is mounted for pivotal motion about a horizontal axis perpendicular to the panel 25 by a lug or pin 42 secured to and extending rearwardly from the rear surface of the door section 25. Normally the plate 38 is biased in a clockwise direction as viewed in FIGS. 3 and 3A about the pin 42 by the tension spring 36 which has its upper end secured to a pin 43 anchored in the plate 38 and its lower end secured to a stationary bracket 44 anchored to the lateral edge of the door 22 at a point below the detent 31. Clockwise biasing of the guide 38 about pivot pin 42 operates, as shown in FIGS. 3 and 3A, to dispose link 40 in a horizontal position against a stop lug 45 extending rearwardly from the rear surface of the door panel 25. The link 40 at its outer end is pinned to the inner end of the detent 31 by a pin 46 and at its inner end is pinned to the upper outer corner of the plate 38 by a pin 47. Thus, the tension spring 36 acting through the pivot plate 38 and the link 40 tends to position the detent 31 in its extended position to engage the saw-teeth 30. In a similar manner, the tension spring 37 operating through the pivot plate 39 and link 41 normally biases the detent 32 to its extended position. The plate 39 is pivotally mounted about a lug 42 extending perpendicularly from the rear surface of the panel 25 and is normally biased by the spring 37 in a counterclockwise direction as viewed in FIG. 3. Link 41 is pinned at its outer end to the inner end of the detent 32 via a pin 46 and at its inner end is pinned to the upper right hand corner of the plate 39 by a pin 47. A lug 45 projecting rearwardly from the rear surface of panel 25 limits upward motion of the link 41 to the horizontal position shown in FIG. 3. Spring 37 at its upper end is connected to the plate 39 via a pin 43 anchored in the plate 39 and at its lower end is connected to the door 22 by a bracket 48.

A cable 50 is provided to simultaneously raise the door 22 to its upper position and move the detents 31 and 32 to their retracted position disengaged from the saw-teeth 30 of racks 29 as shown in FIGS. 4 and 4A. The cable 50, which may be endless, has an upper portion 50-1 which wraps around a pulley 51 mounted for rotation with a horizontal output shaft 52 of an electric motor and gear box assembly 53 stationarily mounted to a frame member 54 of the cash dispenser housing 10. The right hand section 50-2 of the cable 50 at its upper end guides over an idler pulley 55 mounted for rotation about a horizontal axis to a shaft 56 secured to the frame member 54, and at its lower end passes between pulleys 57 and 58 mounted to plate 39 for rotation about horizontal axes. A left-hand section 50-3 of the cable 50 at its lower end passes between pulleys 60 and 61 mounted to plate 38 for rotation about horizontal axes. A lower horizontal cable section 50-4 connects the lower ends of vertical cable sections 50-2 and 50-3.

A plate 62 is mounted for pivotal motion about a horizontal pin 63 fixed to the frame member 54 of the cash dispenser housing 10. Plate 62 has idler pulleys 64 and 65 pinned thereto, and is normally biased by an elongated spring member 66 for rotation about pin 71 in a clockwise direction as viewed in FIG. 3. Spring 66 has its opposite ends respectively secured to the frame member 54 and a pin 67 anchored to the plate 62, with an intermediate portion of the spring 66 positioned below the pin 63. By virtue of the fact that the cable 50 has a portion thereof trained over pulleys 64 and 65, the clockwise biasing motion of the plate 62 functions to eliminate slack in the cable 50. The tension applied to the cable 50 by the biased pulleys 64 and 65 has a tendency to pivot plates 38 and 39 counterclockwise and clockwise, respectively, as viewed in FIG. 3 and thereby retract the detents 31 and 32. However, the force of the spring 66 which causes tension to be applied to the cable 50 to remove the slack therein is-not sufficient to overcome the bias applied to the detents 31 and 32 by tension springs 36 and 37 with the result that springs 36 and 37 contract to maintain the detents in their extended position.

In operation, when the door 22 is in its lowermost, or

fully closed, position shown in FIG. 3 and the motor 53 deenergized, the detents 31 and 32 are in their extended position shown in FIG. 3 and are maintained in such position by the springs 36 and 37 notwithstanding that the cable is under slight tension by the action of the slack-eliminating spring 66 operating through the pivot plate 62 and pulleys 64 and 65 attached thereto. With the detents 31 and 32 in their extended position, the door 22 cannot be raised. Any effort to raise the door will cause the extended detents 31 and 32 to engage or mechanically interfere with the lowermost saw-teeth 30 of stationary racks 29.

When it is desired to move the door from its lowermost, fully closed position shown in FIG. 3 to its raised or open position shown in FIG. 4, the motor 53 is energized to rotate the pulley 51 in a counterclockwise direction as viewed in FIGS. 3 and 4, causing more of the cable 50 to wrap about the pulley 51, effectively winding the cable to shorten its length and increase its tension. The increased tension in the cable 50 applies force to the plate 38 and 39 via pulleys 61 and 58 in a direction to pivot the plates 38 and 39 about pins 42 in counterclockwise and clockwise directions, respectively. Pivotal motion of plates 38 and 39 in the direction indicated pivots links 40 and 41 downwardly and inwardly, in turn retracting detents 31 and 32 from their extended position shown in FIG. 3 to their retracted position shown in FIG. 4. Continued energization of the motor 53 following retraction of the detents 31 and 32 further shortens the effective length of the cable 55, to raise the door from its lowermost position depicted in FIG. 3 to its uppermost position depicted in FIG. 4. When the door 22 has reached its full, open position, a limit switch (not shown) is tripped by the door. The limit switch de-energizes the motor to prevent further upward door motion, and energizes a brake (not shown) which applies braking force to the motor shaft to maintain the door in its open position.

As noted, the force applied by the springs 36 and 37 to detents 31 and 32 must be sufficient to maintain the detents in the extended position shown in FIG. 3 notwithstanding the tension applied to the cable 50 by the slack take-up mechanism which include spring 66, pivoting plate 62 and pulleys 64, 65. However, the force of the springs 36 and 37 must be sufficiently low to enable the tension developed in the cable 50 in the course of raising and lowering the door, due to the weight of the door acting on the cable, to pivot the plates 38 and 39 and thus withdraw or retract the detents 31 and 32 to the position shown in FIG. 4.

Lowering of the door 22 from the raised, open position shown in FIG. 4 to the lowered, closed position shown in FIG. 3 is accomplished by releasing the brake, and energizing the motor 53 in a direction such that the pulley 51 rotates clockwise as viewed in FIGS. 3 and 4. Rotation of the pulley 51 in this direction unwinds the cable, increasing its effective length. This permits the door 22 to move downwardly under its own weight aided by the force of gravity. The weight of the door 22, which is suspended by the cable 50, applies sufficient tension to the cable 50 to maintain the detents 31 and 32 in the retracted position shown in FIG. 4, thereby allowing the door to lower without engagement of the detents and their associated saw-teeth 30. When the door has been lowered to its lowermost position shown in FIG. 3, continued rotation of the motordriven pulley 51 in a clockwise direction removes that portion of the tension in the cable 50 heretofore existing due to the weight of the door 22 suspended by the cable, with the result that the detents are no longer held in their retracted positions. The force applied to the plates 38 and 39 by the springs 36 and 37, which is sufficient to overcome the tension applied to the cable by the slack take-up mechanism 62, 64, 65, and 66, effectively urges the detents 31 and 32 to their outer extended position shown in FIG. 3. In this position, the

door cannot be raised except with the aid of the motor gravity is impeded, delayed or retarded, although not prevented. Specifically, the tension of springs 36 and 37 is selected such that the weight of the door 22, when the tension is removed from the cable 50 by breakage or'the like, will drive the door downwardly, but at a reduced speed caused by the periodic engagement and disengagement of the detents 31 and 32 with successively lower teeth 30 of the tacks 29. Of course, the tension of springs 36 and 37 must not be so large as to positively lock the detents 31 and 32 in engagement with the rack teeth 30 should the cable 50 break or teh tension therein otherwise be removed when the door is in its partically or fully elevated position. By virtue of this feature of the invention, should the cable break when the door is in its elevated position, a customer of the cash dispenser having his hand located between the lower edge of the door 22 and the recess floor will not be injured by virtue of being caught between a rapidly or free-falling door and the cavity recess floor.

Additionally, and by virtue of the fact that the door when being lowered is lowered by the force of gravity under control of a cable rather than being positively driven to its closed position, a customer using the cash dispenser will not be injured should he have his hand located between the lower edge of the door 22 and the cavity bottom 15. Rather, the door will remain in the partially closed position determined by the location of the customers hand until it is removed, whereupon the door will move downwardly to its fully closed position on an intermittent, retarded basis as the extended detents 31 and 32 sequentially engage successively lower teeth 30. Of course, if the downward motion of the door under the action of the motor 53 is interrupted by the user, the direction of the door cannot be reversed to open it by virtue of the engagement of the detents 31 and 32 with the teeth 30 of racks 29.

To enable the door 22 to automatically return to its lower, closed position should an electrical power failure occur when the door is in its raised, upper position, it is essential that the mechanical friction in the motor 53 and associated gearing, if any, be sufficiently low to permit the door, when acted upon by gravity along, to unwind the cable from the motor-driven pulley 50-1, thereby effectively lengthening the cable 50 as is necessary to permit the door to be lowered. With the mmechanical friction of the motor and associated gearing below the level indicated, should an electrical power failure occur when the door 22 is in its raised position, the weight of the door will apply a force on the cable of a magnitude sufficient to unwind the upper cable section 50-1 from the pulley 52. As the cable section 50-1 .unwinds from the pulley 52 due to the weight of the door 22, the door will lower until it reaches its closed position. Under these conditions, there will be sufficient tension applied to the cable by the weight of the door to maintain the detents 31 and 32 in the inner, retracted position. Thus, the door will lower without intermittent engagement of the door-mounted detents and stationary rack teeth. The rate of closing will depend on the exact extent of mechanical friction in the motor 53 and associated gearing, as well as the inertia and friction of the rotating pulley elements about which the cable is trained.

While the invention has been described with respect to selectively covering an opening in a vertical housing wall with a vertically disposed door, it should be understood that the door and housing wall in which the opening is located need not be completely vertical, but rather only have a vertical component sufficiently large to enable the door aided by the force of gravity to move downwardly when being lowered by the cable or under broken cable conditions and further tension the cable sufficiently when being elevated to overcome the force of bias springs 36 and 37 and thereby retract the detents 31 and 32. Accordingly, the term vertical as used herein includes completely vertical, i.e., no horizontal component, as well as inclined positions having both horizontal and vertical components wherein the vertical component satisfies the conditions enumerated above.

The invention has been described, in accordance with a preferred embodiment, as having the detent horizontally slidably mounted to the door and the sawtooth rack stationarily mounted to the cash dispenser housing. It is possible, although not preferable, to mechanically interchange the position of the detents and saw-tooth racks, that is, to stationarily mount the detents to the cash dispenser housing proximate the sides of the opening and horizontally slidably mount the racks to the rear of the door.

What is claimed is:

l. apparatus for selectively controlling access through a protected opening, comprising:

a vertically disposed wall having an opening therein with respect to which access is to be controlled, door configured to prevent access through said opening when positioned to cover said opening,

a vertically disposed guide means proximate said opening in guiding engagement with said door for restricting movement of said door between an upper position in which said opening is uncovered by said door to permit access through said opening and a lower position covering said opening to prevent access through said opening,

abutment means including vertically spaced abutment elements proximate said opening,

a detent mounted to said door for horizontal movement between an extended position engaging said abutment means and a retracted position disengaged from said abutment means,

bias means normally biasing said detent to said extended position into engagement with said abutment means to prevent upward motion of said door,

a motor, and

a cable engaging said motor and said detent for retracting said detent and elevating said door when said motor winds said cable, and for retracting said detent and lowering said door when said motor unwinds said cable,

said door having a mass for tensioning said cable sufficiently to overcome the effect of said bias means for retracting said detent when said motor is operated to wind and unwind said cable and thereby raise and lower said door.

2. The apparatus of claim 1 wherein said bias means is insufficient to continuously maintain said detent in its extended position engaged with a given one of said abutment elements when said door is at least partially raised and said cable untensioned, said bias means being sufficient to cause said detent to sequentially engage successively lower abutment elements when said cable becomes untensioned with said door at least partially raised.

The apparatus of claim 2 wherein said abutment Apparatus for selectively controlling access through a protected opening, comprising:

are:

vertically disposed wall having an opening therein with respect to which access is to be controlled, door configured to prevent access through said opening when located to cover said opening, vertically disposed guide means proximate said opening in guiding engagement with said door for restricting movement of said door between an upper position in which said opening is uncovered by said door to permit access through said opening and a lower position covering said opening to prevent access through said opening,

motor,

cable engaging said motor and door for elevating and lowering said door when said motor winds and unwinds said cable, respectively, said cable being tensioned by the weight of said door during elevating and lowering thereof,

a detent mounted to said door for horizontal movement between an extended and a retracted position,

multiple abutments vertically spaced proximate said opening,

said abutments and detent configured to prevent upward movement, while permitting downward movement, of said door when said detent is in its extended position in engagement with said abutments,

means connecting said cable and detent for retracting said detent when said tensioned cable is elevating and lowering said door, and

means biasing said detent to its extended position only when said cable is untensioned to prevent elevating said door when (a) said motor unwinds said cable, (b) said door is closed, or (c) said cable becomes broken.

5. The apparatus of claim 4 wherein said biasmeans urges said detent toward said abutment means suffi- UMTm STATES PATENT 0mm; CERTHP KCATE 0F QQHREMWN Patent No. 3 747 274 Dated July 24, 1973 Inventods) Charles J. Moorman and Myron D. Goldman It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 9, line 4; (Claim 3), ','included" should read --inclined-.

Signed and sealed this 19th day of February 197M.

(SEAL) Attest: I r e c. MARSHALL DANN EDWARD M'FIETCHERJR' Commissioner of Patents Attesting Offi c e r FORM Po' 'mso (10-59) USCOMM-DC 6037 S-PGD 

1. APPARATUS FOR SELECTIVELY CONTROLLING ACCESS THROUGH A PROTECTED OPENING, COMPRISING: A VERTICALLY DISPOSED WALL HAVING AN OPENING THEREIN WITH RESPECT TO WHICH ACCESS IS TO BE CONTROLLED, A DOOR CONFIGURED TO PREVENT ACCESS THROUGH SAID OPENING WHEN POSITIONED TO COVER SAID OPENING, A VERTICALLY DISPOSED GUIDE MEANS PROXIMATE SAID OPENING IN GUIDING ENGAGEMENT WITH SAID DOOR FOR RESTRICTING MOVEMENT OF SAID DOOR BETWEEN AN UPPER POSITION IN WHICH SAID OPENING IS UNCOVERED BY SAID DOOR TO PERMIT ACCESS THROUGH SAID OPENING AND A LOWER POSITION COVERING SAID OPENING TO PREVENT ACCESS THROUGH SAID OPENING, ABUTMENT MEANS INCLUDING VERTICALLY SPACED ABUTMENT ELEMENTS PROXIMATE SAID OPENING, A DETENT MOUNTED TO SAID DOOR FOR HORIZONTAL MOVEMENT BETWEEN AN EXTENDED POSITION ENGAGING SAID ABUTMENT MEANS AND A RETRACTED POSITION DISENGAGED FROM SAID ABUTMENT MEANS, BIAS MEANS NORMALLY BIASING SAID DETENT TO SAID EXTENDED POSITION INTO ENGAGEMENT WITH SAID ABUTMENT MEANS TO PREVENT UPWARD MOTION OF SAID DOOR, A MOTOR, AND A CABLE ENGAGING SAID MOTOR AND SAID DETENT FOR RETRACTING SAID DETENT AND ELEVATING SAID DOOR WHEN SAID MOTOR WINDS SAID CABLE, AND FOR RETRACTING SAID DETENT AND LOWERING SAID DOOR WHEN SAID MOTOR UNWINDS SAID CABLE, SAID DOOR HAVING A MASS FOR TENSIONING SAID CABLE SUFFICIENTLY TO OVERCOME THE EFFECT OF SAID BIAS MEANS FOR RETRACTING SAID DETENT WHEN SAID MOTOR IS OPERATED TO WIND AND UNWIND SAID CABLE AND THEREBY RAISE AND LOWER SAID DOOR.
 2. The apparatus of claim 1 wherein said bias means is insufficient to continuously maintain said detent in its extended position engaged with a given one of said abutment elements when said door is at least partially raised and said cable untensioned, said bias means being sufficient to cause said detent to sequentially engage successively lower abutment elements when said cable becomes untensioned with said door at least partially raised.
 3. The apparatus of claim 2 wherein said abutment means includes a rack of saw teeth each having a downwardly angled tooth surface and wherein said downwardly included surfaces form at least part of said abutment elements.
 4. Apparatus for selectively controlling access through a protected opening, comprising: a vertically disposed wall having an opening therein with respect to which access is to be controlled, a door configured to prevent access through said opening when located to cover said opening, a vertically disposed guide means proximate said opening in guiding engagement with said door for restricting movement of said door between an upper position in which said opening is uncovered by said door to permit access through said opening and a lower position covering said opening to prevent access through said opening, a motor, a cable engaging said motor and door for elevating and lowering said door when said motor winds and unwinds said cable, respectively, said cable being tensioned by the weight of said door during elevating and lowering thereof, a detent mounted to said door for horizontal movement between an extended and a retracted position, multiple abutments vertically spaced proximate said opening, said abutments and detent configured to prevent upward movement, while permitting downward movement, of said door when said detent is in its extended position in engagement with said abutments, means connecting said cable and detent for retracting said detent when said tensioned cable is elevating and lowering said door, and means biasing said detent to its extended position only when said cable is untensioned to prevent elevating said door when (a) said motor unwinds said cable, (b) said door is closed, or (c) said cable becomes broken.
 5. The apparatus of claim 4 wherein said bias means urges said detent toward said abutment means sufficiently forcefully to retard, but not prevent, downward motion of said door under the force of gravity when said cable is untensioned. 